Fluoroelastomers are currently used in a variety of applications in which severe environments are encountered, including high temperatures and aggressive chemicals; fluoroelastomers are the material of choice for certain sealant parts, for compression joints, for fuel lines, etc.
Final parts made from fluoroelastomers are generally manufactured via extrusion moulding and/or compression moulding techniques; increasing automation of these devices often requires the fluoroelastomer material to be available under the form of free-flowing micronized powder, e.g. for being automatically metered through feeding hoppers and the like, e.g. those which extrusion-moulding or injection-moulding apparatuses are equipped with.
Nevertheless, bare fluoroelastomers cannot provide free flowing micronized pellets: in the absence of suitable additives, the material is too sticky; thus, even if grounding can be suitably achieved at low temperature to yield micronized pellets, once said micronized pellets revert to room temperatures, severe packing and sticking phenomena occurs, so that the material looses its free-flowing character and cannot be notably used in metering devices in processing equipments.
Dusting agents, like notably calcium stearate, are routinely used for obtaining a stable free flowing behaviour, even after long storage at room temperature.
Thus, in document US 2010174011 (DUPONT PERFORMANCES ELASTOMERS LLC) Jul. 8, 2010, in particular in sections [0042] to [0047], mention is made of state-of-the-art methodologies for providing fluoroelastomer-based processing aid compositions (basically, combination of fluoroelastomer and interfacial additive); in these sections, mention is made of cryogenic grinding as technology for downsizing fluoroelastomer crumbs or pellets; the addition of a dusting agent to prevent massing is taught as an essential requirement for obtaining a free-flowing compound.
Nevertheless, usual additives could negatively affect the outstanding properties of the fluoroelastomer itself, including mechanical and sealing properties.